Currently, there are the following common touch-control technologies.
One touch-control technology is mutual capacitance touch sensing technology. As shown in FIG. 1, a touch is determined based on the mutual capacitance by detecting a coupling capacitance between a driving electrode and a receiving electrode. In the case where there is a touch made by a finger, the coupling capacitance Cm1 between the driving electrode and the receiving electrode becomes smaller than the coupling capacitance Cm0 in the case where there is not any touch made by the finger, since the finger may absorb some of the electrical field lines. Thereby, a touch is detected according to that change.
Another touch-control technology is active pen input technology. As shown in FIGS. 2 and 3, the principle of the technology is similar to that of the mutual capacitance touch sensing technology. In the active pen input mode, the active pen is used as the driving electrode and may emit a driving signal. Receiving electrodes intersecting with each other in the touch screen receive the signal from the active pen. When the distance between the active pen and the receiving electrode changes, the coupling capacitance between the active pen and the receiving electrode may also change, and the signal received by the receiving electrode may also change. The position of the pen may be determined by analyzing the signals of the electrodes.
Yet another touch-control technology is In-cell technology. As shown in FIG. 4, the touch-control function and the display function are combined together by integrating the touch-control unit into the pixel of the liquid crystal display device.
In the first two technologies mentioned above, the liquid crystal display device and the touch-control panel are separated. Therefore, the thickness and weight of the product may be increased, which goes against a lighter and thinner product. Moreover, the touch panel may affect the light transmittance and deteriorate the display effect. In the In-cell technology, a layer of touch-control sensing units is embedded into the pixels of the liquid crystal display device. However, the embedded sensing unit may reduce the display area and therefore may deteriorate the display effect.